Electromagnetic brake



H. E. HODGSON ELECTROMAGNETIC BRAKE July 20, 1937.

Filed Feb. 6. 1935 I MM Mwmh A Patented July 20, 1937 UNITED STATES PATENT OFFIQE.

ELECTROMAGNETIC BRAKE Application February 6, 1933, Serial No. 655,422

7 Claims.

This invention relates to improvements in electromagnetic brakes.

The patent to Bernhard EJ Fernow, Jr., No. 1,410,395, issued March 21, 1922, discloses an electromagnetic brake having various desirable characteristics, as for example simplicity, ruggedness, large braking capacity in proportion to its overall dimensions, and arrangement of the actuating parts to minimize the required movements thereof. However, it has been found that brakes of this type are open to various objections. For example, the field member of the operating magnet moves upon operation of the brake, and in practice it has been found that this sometimes results in breakage of connections for the energizing winding and also renders it difficult to install conduits for water-tight enclosure of such connections.

Ihe present invention has among its objects to provide an improved brake having the various desirable characteristics of the brake disclosed in the aforementioned Fernow patent and which overcomes the aforementioned disadvantages thereof.

Another object is to provide an electromagnetic brake having improved adjusting means associated therewith.

Various other objects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates an embodiment of the invention which will now be described, it being understood that the embodiment illustrated may be modified in various respects without departing from the spirit and scope of the appended claims.

In the drawing,

Figure 1 is a side elevational View of a brake embodying the invention, the operating magnet being shown partially in section.

Fig. 2 is an end View of the brake shown in Fig. l, a portion of the operating magnet being broken away and shown in section, and

Fig. 3 is a sectional view on line 3-3 of Fig. 1.

Referring to the drawing, the same illustrates a brake drum I to be secured to a motor or other device to be braked, opposed brake shoes 2 and 3 for frictionally engaging said drumon opposite sides thereof, and vertically arranged levers i and supporting said shoes respectively. The lower ends of the levers 4 and 5 are pivotally mounted upon pins 6 and 1, respectively, carried by a base 8, and an electromagnet 9 mounted upon said base provides for operation of said levers.

Electromagnet 9 is provided with a field element including a stationary magnet frame ill provided with an energizing winding II I, and said magnet frame has cooperating armature members I2 and [3 arranged on opposite sides thereof. Armature I2 is. integral with lever 5, and armature I3 is operatively connected to lever 4 by a link i4, and is provided with a downwardly projecting arm i 5 having its lower end pivotally mounted upon a pin I6 carried by base 8. Thus the armatures l2 and F3 are connected to the brake shoes 2 and 3, respectively, and a coil spring H held under compression between said armatures serves to bias the latter apart to effect setting of said brake shoes against the drum 5. Upon energization of winding II the armatures l2 and 13 are attracted towards each other against the action of spring ll, to thereby release the brake shoes 2 and 3 from drum I.

More specifically, magnetframe H3 is of annular form, and is provided with projecting feet iii-l8 on the under side thereof which are secured by bolts 19 to a pedestal 20 formed on base 8. Said magnet frame is arranged with its axis at substantially right angles to the axis of drum I, and the same is of such diameter as to be substantially included within the vertical space required by said drum. The winding H is wound upon an insulated bobbin 2| which is secured within the opening in magnet frame !0 by screws 22 associated with said frame. As shown in Fig.

3, the screws 22 are provided with fiat heads which engage the right end wall of bobbin 2| 'to hold the same within a counterbore in the right hand face of magnet frame It, and the left end wall of said bobbin abuts a shoulder 23 formed on the interior of said magnet frame.

Winding II is preferably impregnated and sealed in the magnet frame It! with a water-proof insulating compound, and the terminals for said winding are passed through spaced openings in the upper side of said magnet frame intooppositely disposed pocket projections 24 formed on the periphery of said frame. One of the pocket projections 24 is shown in section in Fig. 2, and

each of said pockets has an insulating plate 25 mounted within the same which carries a binding post 26 for connection to one of the winding terminals.

Magnet frame I 0 is provided with annular projections 21 and 28 on opposite sides thereof which overhang the outer edges of armatures l2 and I3, respectively, and each of said armatures has a non-magnetic annular shim 29 secured to the face thereof to prevent sealing of the latter with said magnet frame. The armatures l2 and I3 are also provided with centrally arranged cylindrical pole projections and 3|, respectively, which project into the opening in bobbin 2!, and are of such length as to provide a relatively narrow air gap 32 between the inner ends thereof.

As is apparent, numerous advantages are obtained by arranging the parts of the magnet in the manner above described. Stationary mounting of the magnet frame I l! and its associated winding l l tends to prevent breaking of the winding connections and also facilitates installation of conduits for water-tight enclosure of such connections. Also by arranging the parts of the magnet in the manner above described a magnetic circuit of low reluctance is obtained which tends to increase the efficiency of the magnet.

Spring IT is arranged within a central opening 33 in pole projection 3| and the inner end of said spring bears againsta. washer 34 seated within a shouldered recess 35 in the face of armature 36 while the outer end of said spring bears against a cross bar 36 which is adjustably secured to armature 53 by bolts 3?. A bolt 38 arranged with spring I l is provided for effecting manual release of the brake. Said bolt extends through openings in the washer 34 and cross bar 36, and the inner end thereof is provided with a head which abuts the washer 34, and. is held against turning within the recess 35 in armature I2. The outer end of said bolt has an adjustable nut 40 associated therewith, and as is apparent by screwing said nut inwardly against the cross bar 36 spring I1 may be compressed to release the brake.

As hereinbefore stated, armature I3 is operatively connected to lever 4 by a link l4. Said link has one end pivotally mounted upon a pin 4| carried between projecting lugs 42 on the upper side of armature I3, and the opposite end of said link passes through an opening in the upper end of lever 4 and has an adjustable nut 43 associated therewith which engages a curved surface 44 upon said lever. Nut 43 is held in engagement withthesurface 44 by a spring 45 held under compression between lever 4 and a collar 46 on link l4, and as is apparent adjustment of said nut varies the angular position of lever 4 with respect to armature l3 to thereby vary the throw of brake shoe 2 upon energization of the magnet 9.

To provide for equalization of the travel of the brake shoes .2 and 3 each of the same is adjustably secured to its associated supporting lever. As shown in Fig. 3, brake shoe 3 is provided with spaced lugs 41 and 48 on the outer side thereof which straddle lever 5, and the same is adjustably. secured to said lever by a bolt 49. Bolt 49 is rotatably mounted within an opening in lever 5 and has a pair of eccentric bushings 55 and 5| keyedthe'reto which are rotatable Within alined openings in lugs 41 and 48, respectively. The bushings 50 and 5| are arranged in corresponding angular positions on bolt 4%, and as is apparent by adjusting the angular position of said bolt, brake shoe 3 is adjustable with respect to lever 5 tovary the travel thereof upon energization of the magnet 9. Bolt 49 has a cup washer 52 and a nut 53 associated with one end thereof, and a nut 54 is associated with the opposite end thereof. shown, bushing 50 projects beyond the face of lug 41' so as to be engaged by the nut 54, and the cup washer 52 is arranged to clear the end of bushing 5| and to engage the face of lug 48. Thus as is apparent, upon tightening of the nuts 53 and 54 bushing 55 is clamped against one side of lever 5 to hold bolt 49 in the required angular position and the cup washer 52 clamps the lug 5| on brake shoe 3 against the opposite side of said lever to rigidly secure said brake shoe to said lever. Means similar to that shown in Fig. 3 is also provided for adjustably securing brake shoe 2 to its associated lever 4.

What I claim as new and desire to secure by Letters Patent is:

1. The combination with a brake drum and opposed brake shoes therefor, of actuating means for said brake shoes including an electromagnet having a stationary field element and a pair of pivoted armature members arranged on opposite sides of said element, one of said brake shoes being supported by one of said armature members, and a link operating connection between the other of said armature members and the other of said brake shoes.

2. In a brake, the combination with a drum and opposed brake shoes therefor, a supporting lever for one of said brake shoes, of an electromagnet having a stationary field member and a pair of cooperating armature members pivotally mounted upon opposite sides thereof, one of said armatures supporting the other of said brake shoes, and a link connection between the other of said armatures and said lever.

3. In a brake, the combination with a brake drum and opposed brake shoes therefor, of a supporting base, a pair of levers pivotally mounted upon said base and each supporting one of said brake shoes, actuating means for said brake shoes including an electromagnet having a stationary field element mounted upon said base, and a pair of cooperating armature members arranged on opposite sides thereof, one of said armatures being supported by one of said levers, and the other of said armatures being pivotally mounted upon said base, and a link connection between said latter armature and the other of said levers.

4. In a brake, the combination with a brake drum and opposed brake shoes therefor, of a supporting base, a pair of levers pivotally mounted upon said base, and each having one of said brake shoes adjustably mounted thereon, actuating of said drum and having an annular winding a mounted within an opening therein, the axis of said winding being disposed substantially radially of said drum and in a plane perpendicular to the axis of said drum and adjacent thereto, a pair of movable armature members located at opposite sides of said magnet frame and arranged to be attracted towards each other upon energization of said winding, each of said armature members being connected to one of said brake shoes,

and a spring interposed between said armature members for biasing the same apart.

6. The combination with a brake drum and opposed brake shoes therefor, of a stationary ring shaped magnet frame having an annular winding mounted within the opening therein, said magnet frame being mounted adjacent the periphery of said drum with its axis disposed substantially radially of said drum and in a plane perpendicular to the axis of said drum and adjacent a pair of movable armature members located at oppositesides of said magnet frame and arranged to be attracted towards each other upon energization of said winding, each of said armature members being connected to one of said brake shoes and having a center pole projection thereon extending into the opening in said winding, and a spring arranged centrally with respect to said armature members for biasing the same apart.

7. The combination with a brake drum and opposed brake shoes therefor, of actuating means for said brake shoes including an electromagnet having a stationary magnet winding of annular form mounted adjacent the periphery of said drum and a pair of movable armature members located at opposite sides of said winding and arranged to be attracted towards each other upon energization of said Winding, each of said armature members being operatively connected to one of said brake shoes and said winding having its axis disposed substantially radially of said drum and in a plane perpendicular to the axis of said drum.

HOWARD E. HODGSON.

CERTIFICATE OF CORRECTION.

Patent No. 2,087,478. July 20, 1957.

HOWARD E. HODGSON.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 65, claim 5, strike out the Words "and adjacent thereto"; page 3, first column, line 5, claim 6, after "drum" insert a comma; and cancel the words "and adjacent"; and that. the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 5th day of October, A. D. 1937.

Henry Van Arsdale (Seal) Acting ,Commissioner of Patents. 

